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Appropriate antibiotic treatment should be initiated immediately when there is a suspicion of a tickborne rickettsial disease (TBRD) on the basis of clinical and epidemiologic findings. Treatment should not be delayed until laboratory confirmation is obtained.

If the patient is treated within the first 4-5 days of the disease, fever generally subsides within 24-72 hours after treatment with an appropriate antibiotic (usually in the tetracycline class). In fact, failure to respond to a tetracycline antibiotic suggests that the patient’s condition might not be a TRBD. Severely ill patients may require longer periods before their fever resolves, especially if they have experienced damage to multiple organ systems. Preventive therapy in non-ill patients who have had recent tick bites is not recommended and may, in fact, only delay the onset of disease.

Recommended Dosage

Doxycycline is the drug of choice for treatment of all TBRD in children and adults. The recommended dose is 100 mg per dose administered twice daily (orally or intravenously) for adults or 2.2 mg/kg body weight per dose administered twice daily (orally or intravenously) for children weighing < 100 lbs. (45.4 kg). Intravenous therapy is frequently indicated for hospitalized patients, and oral therapy is acceptable for patients considered to be early in the disease and who can be managed as outpatients. Therapy is continued for at least 3 days after fever subsides and until there is unequivocal evidence of clinical improvement, generally for a minimum total course of 5 to 10 days. Severe or complicated disease may require longer treatment courses.

Treating Children

The use of tetracyclines are no longer considered controversial when treating children. Concerns regarding dental staining after tetracycline therapy have been based primarily on studies conducted during the 1960s. More recent studies, however, have demonstrated that although multiple exposures to tetracycline increase the risk for tooth staining, limited use of this drug has a negligible effect. Because TBRD can be life-threatening and limited courses of therapy with tetracycline-class antibiotics do not pose a substantial risk for tooth staining, the American Academy of Pediatrics Committee on Infectious Diseases revised its recommendations in 1997 and has identified doxycycline as the drug of choice for treating presumed or confirmed RMSF, ehrlichiosis, and anaplasmosis infections in children of any age.

Treating Pregnant Women

Tetracyclines are generally contraindicated for use in pregnant women because of risks associated with malformation of teeth and bones in the fetus and hepatotoxicity and pancreatitis in the mother. However, tetracycline has been used successfully to treat anaplasmosis in pregnant women, and the use of tetracyclines might be warranted during pregnancy in life-threatening situations where clinical suspicion of TBRD is high. Whereas chloramphenicol is typically the preferred treatment for RMSF during pregnancy, care must be used when administering chloramphenicol late during the third trimester of pregnancy because of risks associated with grey baby syndrome. Substantially limited clinical data exist that support the use of other antimicrobials during pregnancy, although rifampin has been used successfully in several pregnant women with anaplasmosis. Clinicians should use caution, however, in ensuring that RMSF can be ruled out because the clinical presentations of RMSF and anaplasmosis are similar, and the comparative effectiveness of rifampin and doxycycline is unknown at this time.

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